Method of producing printed surface covering and printing enamel therefor



F. s. Dl-:ACON ET AL Aug. 30, 1960 22,950,988A

' METHOD OF PRODUCING PRINTEDVSURFACE COVERING 1 AND PRINTING ENAMEL THEREFOR Filed Oct. 9, 1956 4 mm @Aw o T .E MSH VWW. Nl IRW Ifillvlfn..

. f" @ZM ATTORNE METHOD F PRDUCNG PRINTED SURFACE CVEREJG AND PTENG ENAMEL THERE- FR Frederick S. Deacon, Springfield, Pa., and Ralph W.

Wheeier, r., Wilmington, Del., assignors to Congoleum-Nairn inc., Kearny, NJ., a corporation of New York Filed 9ct. 9, 1956, Ser. No. 614,395

llll Ciaims. (Cl. 117-38) This invention relates to enamel printed surface coverings such as are applied to floors, walls and the like and particularly to a method for producing such surface coverings, and to printing enamels useful in their production.

The printing of a decorative wear layer upon a web of fibrous backing material to produce a product with a colorful and attractive design is well known. The printing of the design is usually accomplished by means of a block printing machine. Such a printing operation is carried out by intermittently advancing a web of backing material beneath a series of vertically movable printing blocks which are cut in the form of the design to be printed. Each printing block bears only that part of the design which is to be printed in one particular color. The number of printing blocks is thus a function of the cornplexity and the number of colors in the design. Designs having up to 24 different colors can be printed on conventional block printing machines. l

A large part of the cost of producing a printed surface covering is represented by the cost of the printing enamel used. It is obvious, therefore, that the thinner the paint film deposited on the web the lower will be the manufacturing cost of the printed product. One method of reducing the decorative paint film thickness of the product is to reduce the thickness of paint on the printing block. it has been found, however, that as the paint on a printing block is reduced in thickness, a point is reached where spotty transfer of paint to the web results. The printed product is thus unacceptable. It has been found that a decorative paint film of less than 0.0035 inch in thickness cannot be printed using the conventional block printing process.

There are ways, however, whereby printed surface coverings having a decorative and wear-resistant top layer of less than 0.0035 inch can be produced. One of these involves the process of printing a design on a web of backing material and then bringing a second web into contact with the printed design, thereby transferring a portion of the decoration to the second web, thus producing two sheets bearing the identical printed design but each with about one-half the paint film thickness than that applied by the printing machine. When conventional printing enamels are used in this process, it is found that the transferred design has a grooved and uneven appearance, rendering it unacceptable commercially.

A second way of producing a surface covering with a very thin decorative and wear-resistant layer is to use blocks with printing surfaces in the form of small, spaced points, so that a relatively small proportion of the area of the block actually bears paint to be printed. The design is thus actually printed in the form of separated dots of paint which can at the outset cover as little as one-third of the area to be printed. The paint then can flow together, thus forming a smooth and uniform design. The use of conventional printing enamels in this method results in unsatisfactory blending of the paint on the sheet, thus producing an uneven design and one in which the base sheet is visible through the uncovered spaces between 2O alco the dots. If conventional enamels are thinned with solvent in an attempt to alleviate this situation, the design becomes smeared and is also unacceptable commercially.

It is an object of the invention to provide a printing enamel which can be used in the production of printed surface coverings having a decorative and wear-resistant layer less than 0.0035 inch in thickness.

lt is another object of the invention to produce an inexpensive printed surface covering having a smooth and ungrooved printed decorative layer.

Other objects and the advantages of the invention will appear hereinafter. In accordance with the invention, a printed surface covering having a smooth decorative and wear-resistant layer of less than 0.0035 inch in thickness is produced by utilizing as a printing enamel a blend of solvent, pigments, resins and a modified oil formed by reacting an oil with drying properties with an unsaturated carboxylic acid having from 3 to l0 carbon atoms and thereafter esterifying by reacting with a polyhydroxy hol.

The present invention will be described with reference to the drawing which is a schematic representation of a block printing machine which shows the printing of a decorative design on a first web of backing material followed by transfer of a portion of the design to a second web. v

The block printing machine consists of a bed 11 which extends the entire length and width of the machine. At each of the opposite sides of the bed 11 is an endless belt 12 which is provided with pins 1S at spaced points throughout its length. The belt 12 passes around drums i3, 14 at either end of the machine which are intermittently rotated to advance a web of backing material 16 step by step along the machine. A doctor blade 18 is provided at the front portion of the printing machine. The edge of the doctor blade is maintained in close relation to the face of the advancing web 16, thereby causing a very thin film of paint from a paint pool 19 to be deposited on the web.

The block printing machine is provided with a plurality of vertically reciprocable printing blocks 21 and associated with` each printing block a horizontally reciprocable paint pot 22 provided with a roller partially immersed Within the pot and a pair of doctor blades for limiting the amount of paint picked up by the roller. When the print blocks are at their maximum height, the paint pot with the asociated roller moves beneath the printing block, thereby transferring the paint on the roller to the block. The operation of a block printing machine is conventional and therefore the means for intermittently rotating the drums and for simultaneously reciprocating the paint pots and the print blocks while the drums are at rest are not shown -in the drawing for the sake of simplicity.

After the final printing station of the block printing machine, two rollers 26, 27 are maintained in such a position that a second web of backing material 25 can pass around them and beneath a vertically reciprocable transfer block 28. The rolls are arranged so that there is a slight clearance between the second web and the first web on the printing machine when the transfer blockis in the up position. When the transfer block is depressed, a portion of the paint film on the first web is transferred to the second web. The two printed webs 30, 31 with the identical decoration on each leave the printing machine for subsequent processing, such' as drying.

In the operation of the block printing machine, a first web of backing material is delivered to the printing machine and is engaged by the pins which serve to advance the web along the machine. The web is contacted by the doctor blade which is positioned immediately forward of the paint pool, thus dampening the web with a small amount of paint. The motion of the web along the block printing machine is in a stepwise manner. When the web is at rest, the printing blocks are lowered and deposit a film `of paint upon the web. The. blocks are then raised and the paint pots move beneath the print blocks depositing a tilm of paint on the printing surface thereof. The second web of backing material passes in closely spaced relation to the first web at the end of the printing machine and is engaged by the same pins which engage the first web. When the machine is at rest and the printing blocks are lowered, the transfer block is simultaneously lowered, thus pressingl the two webs together and transferring a portion of the paint lm on the first web to the second web.

Although the block printing machine has been schematically illustrated showing three print stations, it is apparent that the number of printing stations is governed solely by the complexity and diversity of coloration of the design to be printed. Consequently, the printing machine can have any number of printing stations.

A product of similar decorative film thickness to that produced by the transfer technique illustrated in the drawing can be produced by using specially cut printing blocks in a conventional printing machine. These blocks are cut so that the printing surface is in the form of spaced points, which can occupy as little as 2O percent of the cross-section of the printing surface of the block. When the block is wetted with paint and depressed onto a web, the paint over an area to be printed is in the form of spaced dots, which initially cover from about percent to about 50 percent of the web in the area to be printed by the block. The paint then levels and flows together, forming a smooth decorative film of 0.0035 inch in thickness or less when dry.

The webs used are preferably a mass of porous, fibrous material which have been strengthened by impregnation and which have received one or more seal coats to render them smooth, strong sheets not subject to any staining of the surface coat with the impregnating agent. It is preferably that a web of felted iibers be employed. 1 The felt generally is produced' using a Fourdrinier or cylinder paper machine with the thickness of the resulting sheet normally falling in the range from about .02 to about .08 inch. The fibrous material used is normally cellulosic in origin although other fibers can be used including fibers of mineral and animal origin. The sources of cellulosic material can include cotton or other rag material, wood pulp, including both ground wood and chemical wood pulp, paper, boxes, or mixtures thereof, in any proportion. The web can also contain fillers such as wood flour.

The felted fibers are normally strengthened by impregnation. Various bituminous materials are most commonly used due to their low cost. Normally, quantities ranging from 80 percent to about 140 percent by weight of the impregnant based on the bone dry weight of the felt are used although sometimes as little as percent mpregnant will provide a satisfactory product. Numerous bituminous materials are conventional and include asphalts of petroleum or natural origin and tars and pitch residues of vegetable and animal origin. These materials may be crude, blovm or steam distilled. In addition, various natural and synthetic resinous materials can be used for impregnating felt. Suitable resinous impregnants include phenol-formaldehyde and phenolurea resins, polymerized vinyl compounds, such as polyvinyl chloride, polyvinyl acetate and copolymers thereof, cellulose acetate, cellulose nitrate, and'butadiene-styrene, butadiene-acrylonitrile and natural rubber latices, and the like.

The impregnated felt is normally coated with one or more seal coats designed to seal against any migration of impregnant to the surface of the sheet and also to provide a smooth surface free of any loose ends of fibrous material. The seal coats are commonly of either the oleoresinous or latex type. In an oleoresinouS. Sal wat,

the vehicle can contain dispersed in solvent any of the drying oils and resins which after application dry to a hard, tough, solid consistency. In the case of a seal coat of the latex type, the vehicle comprises an aqueous emulsion of a rubber latex such as natural rubber, butadiene-styrene copolymer and the. like. These vehicles are conventionally used in conjunction with inert fillers such as Whiting, clay, wood iiour, limestone, and titanium dioxide, zinc oxide, and other inorganic and organic pigments, and the like. While it is preferred that the felt be coated with two coats of a sealing material, any number of coats can be used.

The web is preferably moistened with a thin paint film at the start of the printing machine. Normally, a paint similar in composition to that used as a printing enamel is used. This moistening of the web prior to printing is desirable in effecting flow of the printing enamel.

The printing enamel comprises a blend of solvent,

pigments, resins, and a modified oil. It is essential in.

order that the printing enamel have the necessary flow characteristics required in the production of a thin printed decoration upon a web of backing material that the paint contains as its drying oil component a modified oil formed by reacting an oil with drying properties with an unsaturated carboxylic acid having from 3 to 10 car-bon atoms and thereafter esterifying by reacting with a polyhydroxy alcohol. Any oil or mixture of oils with drying properties, that is, drying and semi-drying oils, can be used. This includes tung oil, perilla oil, soybean oil, I

linseed oil, whale oil, oiticica oil, hempseed oil, walnut oil, saiower oil, dehydrated castor oil, herring oil, poppyseed oil, menhaden oil, sardine oil, and the like, and also includes chemically treated oils, such as tall oil esterified with a polyhydric alcohol such as glycerol, sorbitol, pentaerythritol, ethylene glycol, and the like.

The oil'with drying properties is reacted with from about 5 to about 30 percent by weight of an unsaturated carboxylic acid having from 3 to l() carbon atoms, such as acrylic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, angelic acid, glutaconic acid, itaccnic acid, aconitic acid, muconic acid, and the like. The acid can be added or can be present in the reaction mixture as the corresponding anhydride. The condensation reaction is carried out by heating the oil with the acid -for a period of from about l0 minutes to about 5 hours at a temperature between about F. and about 300 C. The reaction is preferably carried out in a pressure autoclave since when low molecular weight unsaturated acids are used, the reaction temperatures will be above the atmospheric boiling point temperature of the acid, thus requiring pressure operation in the autoclave. Pressure operation for the reaction will occur in the case of the reaction of an oil with maleic or fumarie acids which are the preferred acids for use in the invention.

The reaction mixture is preferably esteried with a polyhydroxy alcohol to remove a substantial amount of the free acid present due to the unsaturated carboxylic acid used in the reaction. The polyhydroxy alcohols preferably contain from 2 to 6 carbon atoms and two or more hydroxy groups. Typical examples of suitable compounds are ethylene glycol, propylene glycol, glycerol, sorbitol, pentaerythritol, mannitol and the like. In order that the printing enamel formulated from the modified oil have satisfactory alkali resistance, which is a highly important property in a printed surface covering, it is preferred that the modified oil be neutral or have an acid number of at least no greater than about 20. Acid number is defined as the number of milligrams of potassium hydroxide required to react with 1 gram of material.

Although the reaction is preferably carried out by reacting an oil with an unsaturated acid, followed by esteriication with a polyhydroxy alcohol, the ingredients` can all be present in the reaction mixture simultaneously, or tthe unsaturated acid can be addedin the form of a U complete or partial ester. Also, in the case of the use of a small amount of a high molecular weight, unsaturated acid, treatment with the alcohol may not be required to produce a treated oil having an acid number of less than about 20.

It is important in the preparation of a paint that can be used in the printing of a decorative and Wear-resistant layer of less than 0.0035 inch in thickness that the paint contain no raw or heat-bodied drying oils. For most effective results, the drying oil content of the paint should consist solely of a modified oil as disclosed above. However, a portion of the modified oil can be replaced by an air-blown drying oil if desired. Such an air-blown oil is made by blowing an oxygen containing gas through a supply of an oil with drying properties maintained at a temperature of between about 100 F. and about 200 F.

The solvent used in the printing enamel can comprise any of the solvents or thinners normally present in paints or mixtures thereof, such as turpentine, naphtha, kerosene, benzene, toluene, mineral spirits and the like. The printing enamel will normally contain from about 20 to about 40 percent solvent based on the weight of the enamel, not including pigments. A particularly effective range is from 25 to 35 percent solvent.

The resin content can be made up of the various synthetic and natural resins and gums which are conventionally used in enamels or mixtures thereof, such as alkyd resins, including the reaction products of phthalic, isophthalic, terephthalic, sebacic, adipic, succinic, oxalic, fumarie, citric, glutaric, diglycollic, maleic, camphoric, dilactic, pimelic, suberic, `azelmc acids, and the like with polyhydric alcohols such as sorbitol, ethylene glycol, propylene glycol, pentaerythritol, glycerol, butylene glycol, trimethylene glycol, diethylene glycol, triethylene glycol, and the like; phenolic resins, including the reaction products of phenols, such as phenol, o-, p, and m-cresol, the xylenols, pyrogallol, resorcinol, the naphthols, and the like with aldehydes, such as acetaldehyde, formaldehyde, `acrolein, isobutyraldehyde, furfural, paraldehyde, and the like; coumarone-indene resins; ureaformalde hyde resins, such as obtained by reacting amides, including urea, thiourea, ethylideneurea, naphtnalene monosulphonamide, and the like with aldehydes such as listed under the phenolic resins above; melamine resins; vinyl resins, such as polymers and copolymers of vinyl chloride, vinylidene chloride, vinyl acetate, vinyl butyrate, and the like; polymers and copolymers of acrylic and substituted acrylic acids; and the like.

The paint also contains conventional pigments, extenders, and fillers in conjunction with suitable binders and thinners. Pigments are chosen according to the color desired and can include any of the organic and inorganic types well known in the paint art. Such wellknoWn pigments as lead cliromate, zinc cliromate, lead molybdate, titanium dioxide, zinc oxide, zinc sulfide, copper ferrocyanide, the ferrie ferrocyanide complexes, tolfuidene red, copper phthalocyanine can be used. These pigments are conventionally blended with extenders such as calcium sulfate, barium sulfate, lead sulfate and magnesium oxide. -Such fillers as chalk, Whiting, and clay can be used as desired.

in the formulation of a printing enamel in accordance with the invention, the consistency of the enamel must be comparatively thin and within closely prescribed limits. It is preferred that the consistency be such that when the quantity of paint filling a ring 0.75 inch inside diameter by 0.5 inch long is released upon a smooth plate maintained at an angle of 30 with the horizontal, the leading edge thereof travels between about and about l2 inches in 30 seconds. The most effective range for this distance of travel is from 7 to 10 inches in 30 seconds. This distance of travel is commonly referred to as the "fiow of the paint. In contrast to this comparatively thin consistency is the flow of conventional printing enamels which normally is in the range of from 11/2 to 8 inches in 60 seconds.

The printing enamel is formulated so that the ratio of modified oil to total resin in the paint is between about 0.5 to 1 to about 5 to 1. A particularly effective ratio of treated oil to resin is from 1.5 to 1 to about 3 to 1.

Example 1 A modified oil suitable for use in the invention -is produced by lheating pounds of soybean oil with 9.8 pounds of crotonic acid for 2 hours and 30 minutes in a pressure autoclave at 250 C. The reaction mixture is cooled to C. and 2.8 pounds yof ethylene glycol is added with agitation of the mixture until the reaction is complete. The resulting product has an acid number of 12.

Example 2 A modified oil suitable yfor use in the invention is produced by heating 750 pounds of linseed oil with 50 pounds of maleic `acid for 45 minutes at 225 C. in a pressure autoclave. To the hot reaction mixture is added 40 pounds of glycerol 4and the mixture is stirred until the reaction is complete. The product has an acid number of 14.

Example 3 A web of asphalt saturated felted cellulosic fibers which have been double seal coated with oleoresinous seal coats is printed on a standard block printing machine in a floral pattern design requiring 12 printing stations. The printing enamels are prepared as follows:

650 pounds of pigments, comprising zinc oxide, titanium calcium sulphate and calcium sulphate were ground with 335 pounds of vehicle on a standard three-roll mill. The vehicle was prepared by heating 70 pounds of the modified oil of Example 2 with 36 pounds of phenolic 4and alkyd resins to a temperature of 300 F. until the resins dissolved. The solution was cooled to 200 F. and 5 3 pounds of mineral spirits and 0.5 pound of cobalt and manganese driers and conventional anti-Skinning agents were added with stirring. The mixture or paste of pigments and vehicle was tinted with various tinting pigments to produce the different colors required in the printing process. Each tinted paste was then thinned with additional vehicle formulated as described above to a flow of S inches.

After the twelfth and final printing station of the block printing machine, the printed web is intermittently contacted with a second web of asphalt saturated felted cellulosic fibers, thereby transferring a portion of the printed 4design from the first web tothe second web. The two printed webs are passed to heating `ovens maintained at a temperature of 150 F., where the paint films are dried overa period of 16 hours.

The two printed webs each bear smooth decorative and wear-resistant paint films of 0.0025 inch in thickness.

Example 4 A series of printing enamels for use in preparing a decorative surface covering was formulated as indicated in Example 3 except that the vehicle comprised 35 pounds of the modified oil of Example 1 and 35 pounds of anoilobtained by blowing linseed oil with air at a temperature of F. in place of the 70 pounds of modifiedoil of Example 2.

A design was printed on a block printing machine yand a portion thereof was transferred to a second web in accordance with the procedure outlined in Example 3. After drying, the two webs each bore ungrooved decorative and wear-resistant paint films of about 0.0027 inch in thickness.

Example 5 A series of printing enamels was formulated as indicated in Example 3. A conventional block printing machine was modified by providing blocks cut in the form of spaced pins. The design was printed in the form of spaced dots of paint which immediately after being printed covered 35 percent of the area to be covered by the particular color used. The printed sheet after being dried had a smooth and uniform decorative and wearresistant paint film of 0.0030 inch in thickness.

Although this invention has been described with reference to a standard block printing machine, it is obvious that it is `adaptable to other printing processes, such as a rotary printingprocess. Anydeparture from the above description which conforms to the present invention is intended to be included Within the scope of the claims.

We claim:

1. A printing enamel for use in block printing a decora- -tive design upon a web of backing material in the production of a printed Surface covering having a smooth and unblemished decorative paint layer of less than 0.0035 inch in thickness upon a web of backing material which comprises a mixture of solvent, pigments, resins and a modified oil formed by reacting an oil with drying properties with about to about 30 percent of its weight of `an unsaturated carboxylic acid containing from 3 to 10 carbon atoms and thereafter esterifying by reaction with a polyhydroxy alcohol, said enamel having a ratio of modified oil to resins of. about 0.5 to l to about 5 to 1 and being of Such consistency that when a quantity thereof filling ka ring 0.75 inch inside diameter by 0.5 inch long is released upon a smooth surface maintained at an angle of 30 with the horizontal, 4the leading edge of said quantity travels from about 5 to about 12 Iinches -in 30l seconds.

2. A printing enamel for use in block printing a decorative design upon a Webof backing material in the production of a printed surface covering having a smooth and unblemished decorative paint layer of less than 0.0035 inch in thickness upon a web of backing material which comprises a mixture of solvent, pigments, resins and a modified oil, there being from about 20 percent to about 40 percent solvent based on the weight of pigment-free enamel, said enamel having a ratio of modified oil to resins of from about 0.5 to 1 to about 5 to 1 and being of such consistency that when a quantity thereof filling a ring 0.75 inch inside diameter by 0.5 inch long is released upon a smooth surface maintained lalt an angle of 30 with the horizontal, the rleading edge of said quantity travels from about 5 to about 12 inches in 30 seconds, said modified oil being formed by reacting an oil with drying properties with about 5 to about 30 percent of its Weight of an unsaturated carboxylic acid containing from 3 to 10 carbon atoms and thereafter esterifying by reaction with a polyhydroxy alcohol.

3. Aprint-ing enamel for use in block printing a decorative design upon -a web of backing material in the production of a printed surface covering having a smooth and unblemished decorative paint layer of less than 0.0035 inch in thickness upon a web of backing material which comprises a mixture of solvent, pigments, resins and a modified oil, there being from 2S percent to 35 percent solvent based on the weight of pigment-free enamel, said enamel having a ratio of modified oil to resins of from 1.5 to l to about 3 to 1 and being of such consistency that when a quantity thereof filling `a ring 0.75 inch inside diameter by 0.5 inch long is released upon a smooth surface maintained at an angle of 30 with the hor-izontal, the leading edge of said quantity travels from 7 to-10 inches in 30 seconds, said modified o-il being formed by reacting an oil with drying properties with about 5 to about 30 percent of its Weight of an unsaturated carboxylic -acid containing from 3 to 10 carbon atoms and thereafter esterifying by reaction with a polyhydroxy alcohol having from 2 to 6 carbon atoms to yield a modied oil having an acidY number of no greater than about 20.`

4. 'Aprinting enamel for use `in block printing a decora.-

81 tive design upon a web of backing material in the production of a printed surface covering having a smooth and unblemished decorative paint layer of less than 0.0035- inch in thickness upon a web of backing material which comprises a mixture of solvent, pigments, resins: and a4 modified oil, there being from about 20 percent to about 40 percent solvent based on the weight of pigment-free enamel, said enamel having a ratio of -modifiedoil to said modified oil being formed by reacting an. oil withdrying properties with about 5 to about 30 percent of its Weight of maleic acid 4and thereafter esterifying by reaction with -a polyhyd-roxy alcohol to yield a modified oil having an acid number of no greater than about 20.

5. A printing enamel for use in block printing a decorative ldesign upon a web of backing material in the production of a printed surface covering having `a smooth and unblem-ished decorative paint layer of less than 0.0035 inch in thickness upon a web of backing material which comprises a mixture of solvent, pigments, resinsl and a modified oil, there being from 25 percent to 35 percent solvent based on the weight of pigment-free, enamel, said enamel having a ratio of modified oil to resins of from 1.5 to l to about 3 to l and being of suchv consistency' that when a quantity thereof fillingl a ring 0.75 inch inside diameter by 0.5 inch long is released upon a smooth surface maintained at an angle of 30 with the horizontal, the leading edge of said quantity travels from 7 to l0 inches in 30 seconds, said modified oil being formed by reacting an oil with drying propertieswith about 5 to about 30 percent of its weight of maleic acid and thereafter esterifying by reaction with a polyhydroxy alcohol having from 2 to 6 carbon atoms to yield a modified oil having an acid number of no greater than about 20.

6. In a process of producing a covering for floors, Walls and the like having a decorative and wear-resistant surface layer of less than 0.0035 inch in thickness by printing a decorative design with a printing enamel upon a web of backing material which comprises printing said design upon the web in the form of spaced dots of enamel which immediately after printing cover from 20 percent to 50 percent of the area to be covered, the improvement which comprises utilizing as the enamel a mixture of solvent, pigments, resins and a modified oil formed by reacting an oil with drying properties with about 5 to about 30 percent of its weight of an unsaturated carboxylic acid containing from 3 to 10 carbon atoms and thereafter esterifying by reaction with a polyhydroxy alcohol to yield a modified oil having an acid number of no greater than labout 20, said enamel having a ratio of modified oil to resins of about 0.5 to 1 to about 5 to l `and being of .such consistency that when a quantity thereof filling a ring 0.75 inch inside diameter by 0.5 inch long is released upon a smooth surface maintained at an angle of 30 with the horizontal, the leading edge of said quantity travels Ifrom about 5 to about 12 inches in 30 seconds, said improvement resulting in a covering product having a smooth and unblemished surface.

7. In a process of producing -a covering for floors, Walls and the like having a decorative and wear-resistant surface layer of less than 0.0035 inch in thickness by printing a ydecorative design with a printing enamel upon a Web of backing material which comprises printing said design upon the web in the form of spaced dots of enamel which immediately after printing cover from 20 percent to 50 percent of the area to be covered, the improvement which comprises utilizing as the enamel a mixture of solvent, pigments, resins: and a modified oil formed by reacting an oil with drying properties with about to about 30 percent of its weight of an unsaturated carboxylic acid containing from 3 to 10 carbon atoms and thereafter esterifying by reaction with a polyhydroxy alcohol to yield a modified oil having an acid number of no greater than about 20, said enamel having lfrom 25 to 35 percent solvent based on the weight of pigment-free enamel and having a ratio of modilied oil to resins of from 1.5 to 1 to about 3 to 1, and said enamel being of such consistency that when a quantity thereof filling a ring 0.75 inch inside diameter by 0.5 inch long is released upon a smooth surface maintained `at an angle of 30 with the horizontal, the -leading edge of said quantity travels from 7 to 10 inches in 30 seconds, said improvement resulting in a covering product having a smooth and unblemished surface.

8. The process according to claim 8 wherein the unsaturated carboxylic acid having from 3 to 10 carbon atoms is maleic acid and the polyhydroxy alcohol has from 2 to 6 carbon atoms.

9. In a process of printing `a decorative design with a printing enamel upon a lirst web of backing material and thereafter transferring a portion of said printed design to a second web of backing material by contacting said second web with the printed design upon said first web, thereby producing two webs having identical designs printed thereon, the improvement which comprises utilizing as the enamel a mixture of solvents, pigments, resins and a modified oil formed by reacting an oil with drying properties with about 5 to about 30 percent of its weight of an unsaturated carboxylic acid containing from 3 to 10 carbon atoms and thereafter esterifying with a polyhydroxy alcohol to yield a modified oil having an acid number of no greater than about 20, said enamel having from about to about 40 percent solvent based on the weight of pigment-free enamel and having a ratio of modified oil to resins of from about 0.5 to 1 to about 5 to 1, and said enamel being of such consistency that When a quantity thereof lling a ring 0.75 inch inside diameter by 0.5 inch long is released upon `a smooth surface maintained at an angle of 30 with the horizontal, the leading edge of said quantity travels from about 5 to about 12 inches in 30 seconds, said improvement resulting in twoprinted webs having smooth and unblemished decorative paint layers less than 0.0035 inch in thickness.

10. In a process of printing a decorative design with a printing enamel upon a first web of backing material and thereafter transferring a portion of said printed design to a second web of backing material by contacting said second web with the printed design upon said rst web, thereby producing two webs having identical designs printed thereon, the improvement which comprises utilizing as the enamel a mixture of solvent, pigments, resins and a modied oil formed by reacting an oil with drying properties with about 5 to about 30 percent of its weight of an unsaturated carboxylic acid containing from 3 to 10 carbon atoms and thereafter esterifying with a polyhydroXy alcohol to yield a modiied oil having an acid number of no greater than about 20, said enamel having from 25 to 35 percent solvent base'd on the weight of pigmentfree enamel and having a ratio of modified oil to resins of from 1.5 to 1 to about 3 to 1, and said enamel being of such consistency that when a quantity thereof illing a ring 0.75 inch inside diameter by 0.5 inch long is released upon a smooth surface maintained `at an angle of 30 with the horizontal, the leading edge of said quantity travels from 7 to 10 inches in 30 seconds, said improvement resulting in two printed webs having smooth and unblem- `ished decorative paint layers less than 0.0035 inch n thickness.

11. The process according yto `claim 10 wherein the unsaturated ycarboxylic acid having from 3 to 10 carbon atoms is maleic acid.

References Cited in the iile of this patent UNITED STATES PATENTS 1,495,146 Ariente et al. May 27, 1924 1,959,363 Hopkins May 22, 1934 1,960,220 Hopkins May 22, 1934 2,252,399' Durant Aug. 12, 1941 2,280,242 Kropa et al Apr. 21, 1942 2,305,224 Patterson Dec. 15, 1942 2,332,898 DAlelio Oct. 26, 1943 2,392,710 Wakeford et al. Ian. 8, 1946 2,407,479 DAlelio Sept. 10, 1946 2,418,633 Gould Apr. 8, 1947 2,423,042 Muskat June 24, 1947 '2,435,429 Evans et al Feb. 3, 1948 2,504,845 Keyes Apr. 18, 1950 2,586,344 Keyes Feb. 19, 1952 2,618,616 Tess et al Nov. 18, 1952 OTHER REFERENCES Beck: Industrial and Eng. Chem., February 1944, vol. 36, No. 2, pp. 157-158. Copy in Div. 50. 

1. A PRINTING ENAMEL FOR USE IN BLOCK PRINTING A DECORATIVE DESIGN UPON A WEB OF BACKING MATERIAL IN THE PRODUCTION OF A PRINTED SURFACE COVERING HAVING A SMOOTH AND UNBLEMISHED DECORATIVE PAINT LAYER OF LESS THAN 0.0035 INCH IN THICKNESS UPON A WEB OF BACKING MATERIAL WHICH COMPRISES A MIXTURE OF SOLVENT, PIGMENTS, RESINS AND A MODIFIED OIL FORMED BY REACTING AN OIL WITH DRYING PROPERTIES WITH ABOUT 5 TO ABOUT 30 PERCENT OF TIS WEIGHT OF AN UNSATURATED CARBOXYLIC ACID CONTAINING FROM 3 TO 10 CARBON ATOMS AND THEREAFTER ESTERFYING BY REACTION WITH A POLYHYDROXY ALCOHOL, SAID ENAMEL HAVE A RATIO OF MODIFIED OIL TO RESINS OF ABOUT 0.5 TO 1 TO ABOUT 5 TO 1 AND BEING OF SUCH CONSISTENCY THAT WHEN A QUANTITY THEREOF FILLING A RING 0.75 INCH INSIDE DIAMETER BY 0.5 INCH LONG IS RELEASED UPON A SMOOTH SURFACE MAINTAINED AT AN ANGLE OF 30* WITH THE HORIZONTAL, THE LEADING EDGE OF SAID QUANTITY TRAVELS FROM ABOUT 5 TO ABOUT 12 INCHES IN 30 SECONDS. 